Book Image

PostgreSQL High Availability Cookbook - Second Edition

By : Shaun Thomas
Book Image

PostgreSQL High Availability Cookbook - Second Edition

By: Shaun Thomas

Overview of this book

Databases are nothing without the data they store. In the event of a failure - catastrophic or otherwise - immediate recovery is essential. By carefully combining multiple servers, it’s even possible to hide the fact a failure occurred at all. From hardware selection to software stacks and horizontal scalability, this book will help you build a versatile PostgreSQL cluster that will survive crashes, resist data corruption, and grow smoothly with customer demand. It all begins with hardware selection for the skeleton of an efficient PostgreSQL database cluster. Then it’s on to preventing downtime as well as troubleshooting some real life problems that administrators commonly face. Next, we add database monitoring to the stack, using collectd, Nagios, and Graphite. And no stack is complete without replication using multiple internal and external tools, including the newly released pglogical extension. Pacemaker or Raft consensus tools are the final piece to grant the cluster the ability to heal itself. We even round off by tackling the complex problem of data scalability. This book exploits many new features introduced in PostgreSQL 9.6 to make the database more efficient and adaptive, and most importantly, keep it running.
Table of Contents (18 chapters)
Title Page
About the Author
About the Reviewer
Customer Feedback

Incorporating the second LVM layer

In this recipe, we are going to create the second of our two LVM abstraction layers. While the first layer provides an elastic base for DRBD, this one will provide most of the LVM functionality that we will actually use on a regular basis.

Tasks such as creating filesystem snapshots or reorganizing data are within the domain of the second layer. This is because we create the filesystem on top of this second LVM definition. We can mount or otherwise manipulate a snapshot like any other filesystem. If we tried to create a snapshot with the first LVM layer, we would still have a snapshot, but it would be of an unreadable DRBD binary blob.

With that in mind, let's add the LVM layer necessary for filesystem manipulation.

Getting ready

Please follow all previous recipes before starting.

How to do it...

Perform these steps only on pg1 as the root user:

  1. Register /dev/drbd0 as an LVM physical device, using this command:
pvcreate /dev/drbd0
  1. Create a single volume group to...